1. Field of the Invention
This invention relates to structures for improving the aerodynamic shape of vehicles, and more particularly to a deployable structure that is easily opened to improve the aerodynamic shape of a vehicle, and closed when not used. When closed, the structure nests unobtrusively against the vehicle.
2. Description of the Art
The amount of power needed to move a vehicle over land or through the air increases with the speed of the vehicle, due to aerodynamic drag. The amount of power necessary to overcome aerodynamic drag directly translates into increased fuel consumption, and thus cost of operation.
Because of this, attention has been directed at reducing the aerodynamic drag of a wide variety of transport vehicles, such as trucks. The form drag of a truck is related in part to the shape of the frontal parts, such as the cab and the abruptness of its transition to the trailer or container. There have been a variety of improvements made to improving the aerodynamic shape of these parts, such as by making the hood, windscreen, fenders etc. more streamlined in form, as well as by adding fairings to the cab roof, or the front of the truck box.
Another significant contributor to the form drag of a truck is the drag associated with the rear of the trailer. A typical trailer box will terminate with a large rectangular surface. This shape causes an area of reduced pressure to be created behind the trailer box as it moves over the highway, the result of which is to generate a retarding force that must be overcome with additional engine power, and thus additional fuel.
Accordingly, there have been efforts directed at adding a fairing to the rear of the trailer box to lessen the reduced pressure area created at the rear, and thus improve the over the road fuel efficiency. However, the business of trucking is highly competitive and sensitive to operating costs, which include not only fuel costs but also capital costs and costs associated with any tasks that the driver or others must do to operate the truck and performing loading and unloading operations. In this regard, a one piece fairing covering the back of the trailer box will typically also cover the loading/unloading doors. Therefore, such a fairing is cumbersome if permanently mounted to the trailer box. Likewise, dismounting and securing the fairing each time a loading/unloading operation is to be performed takes extra time, may require additional equipment to assist in the movement, stowage and positioning of the relatively large fairing, and may not be within the skills of the driver and/or loaders.
Attempts have also been made to make the rear fairing in some way retractable so that it does not impair off-highway activities. However, these efforts have to date not yielded devices having widespread use. There is therefore still a need for a rear fairing for transportation vehicles, such as trucks and truck trailer boxes, which ably accommodates both aerodynamic and ease of use considerations to provide the user sufficient increased profitability to warrant its use.
The present invention is a deployable fairing that is made from two principal assemblies that are mirror images of each other. Each assembly comprises a first semi-rigid surface having a curved edge, with the first semi-rigid surface secured to the vehicle in a manner that permits the first semi-rigid surface to assume two positions: a first position adjacent the vehicle, and a second position extended from the vehicle. There is further provided a first joint structure which spans the first semi-rigid surface, to permit the first semi-rigid surface to be folded when in the first position and unfolded when in the second position. As described in more detail below, this first semi-rigid surface advantageously acts as a single panel when fully deployed, while converting to two panels to facilitate retraction and storage.
Each assembly also includes a second semi-rigid surface having a curved edge, with the second semi-rigid surface secured to the vehicle in a manner that permits the second semi-rigid surface to assume a first position adjacent the vehicle and a second position extended from the vehicle. The first and second semi-rigid surfaces are joined together at their first and second curved edges by a second joint structure adapted to permit the first and second semi-rigid surfaces to fold approximately together when the first and second semi-rigid surfaces are adjacent the vehicle.
Utilizing these and other aspects of the invention disclosed herein, the aerodynamic and rigidifying aspects of the fairing design each contribute to enhance the other. The truck operator can readily deploy the fairing prior to highway travel, while at the same time readily stow the fairing against the trailer box prior to approaching a loading dock, opening doors and loading or unloading.